In wireless networks, nodes find themselves able to broadcast to multiple neighbors at once. Yet multicast routing, as it exists today, ignores the basic nature of the broadcast medium inherent to wireless communications. Most multicast routing relies on unicast constructs on top of which a multicast group is overlaid. The unicast tree is generated via a Dijkstra-type method. A Dijkstra-type method is a graph search method that solves the single-source shortest path problem for a graph with non-negative edge path costs, producing a shortest path tree. The Dijkstra-type method may be used to reach multicast targets. The unicast tree is inspected so that at each hop, transmissions can be combined and minimized. This results in marked inefficiencies and non-optimal costs. Other techniques are non-optimal and generally fall along the Shortest Path First (SPF) or Steiner tree problem. A Steiner minimal tree is defined to be the minimal cost sub-graph tree spanning a given subset of nodes in a graph. Still other existing techniques may include Kou, Markowsky & Berman (KMB) method (based on other paired shortest paths among the Steiner points), greedy method (makes the locally optimal choice at each stage to find a global optimum), finding central nodes, etc.
Losses result in extra retransmissions which create additional recovery traffic and increase the delivery latency. These extra transmissions are due to the underlying multicast tree loss characteristics, which entail higher routing costs and delays. Concepts of short-path routing are inherently attached to unicast trees, which do not take into account the ability of certain nodes to reach one or more neighbors with one transmission
Nodes with multiple transceivers assigning multiple frequencies find themselves able to broadcast to multiple and separate groups of neighbors at once. Yet multicast routing, as it exists today, ignores the basic nature of the broadcast medium inherent to wireless communications.